A system is required for the colour inspection of pharmaceutical tablets while they are being automatically counted into containers. When filling containers with pharmaceutical tablets, the tablets must be inspected for the correct colour, as the colour is an indication of their active ingredient or dose. The actual colour used in any particular situation is manufacturer dependent.
Since a rogue tablet could typically be left un-noticed on a ledge from a previous use of the filling apparatus when a different tablet was being filled into containers, the most effective point at which to inspect tablets in the filling process should be as close to their entry point to the container, typically a bottle or plastic container, as possible.
It is known that a typical filling machine has apparatus for separating the tablets in to a single-file, termed as “singulating”, and then counting the tablets as they pass through a sensing device on their way into the container. When the required number of tablets has entered the container, a mechanism intercepts the flow while the container is replaced by the next empty one.
Such a machine often has a multiplicity of such singulating, sensing and intercepting devices working in parallel, in order to increase the overall rate of filling.
Conventional colour-sensing cameras are often mounted above the singulating device, for example, being a vibrating tray having multiple V shaped channels, with each channel transporting one row of tablets.
US Patent Application US2009/0056825A1 discloses the use of a vision system mounted above the product whilst it is on the singulating device.
These known systems have the following shortcomings.
The vision system is only capable of determining the colour of the aspect of the tablet that is nearest to them. One aspect of the tablet is hidden against the singulating device.
This is particularly pertinent when considering bi-layer tablets which are usually two colours, for example top blue and bottom white, and which are increasingly common in the pharmaceutical industry.
While a vision system could be set so as to accept blue and/or white tablets it could not detect the most common manufacturing defect of bi-layer tablets, being de-lamination. This system would consider a de-laminated or half thickness tablet as one blue and one white product.
The arrangement and mounting of the vision system does not allow it to inspect at a sufficiently late position in the process.
High levels of illumination are required. Such illumination dictates that covers are used to prevent eye-damage to the user. The covers are also required to eliminate the effects of ambient lighting. The covers cause difficulty in cleaning the machinery.